This invention relates to a method and apparatus for traversing one or more strands at high speed to form continuous restrained webs having transverse strands in a variety of patterns. More particularly, it relates to a method suited to forming restrained webs of orthogonal pattern in a more positive manner and without the tendency to strand abuse associated with prior high speed equipment.
Products, such as paper and nonwoven fabric, frequently are reinforced with one set of strands in the long direction of the web and a second set in the transverse direction. Maximum efficiency and product uniformity dictate that the strands be spaced equally and of identical length to assume equal sharing of applied loads. Webs of transverse strands held by pins or other selvage restraining elements on a conveyor can be treated readily and combined with a machine direction warp of strands or a sheet of paper like material, the assembly being bonded together with adhesives or other means.
Many prior devices have utilized reciprocating mechanisms that are severely speed limited. Some employ strand carriers that pass between selvage pins, requiring wide spacing of the pins and precluding close spacing of the transverse strands. Others carry the strands over the tops of the pins and require a separate high speed action across the strands to deposit them around the pins. Such sudden action across the strands tends to damage them and lose control of the positioning, particularly when the same action serves also to discharge the strands from the carrier.
Prior machines for traversing strands to form webs have required considerable space beyond the width of the web. The strand traversing equipment, generally, is a component of a long processing line, so that the added width results in wasted space throughout the remainder of the production line.
My present invention has as an objective the achievement of high speed through the traversing of strands with a mechanism using nothing but continuous rotary motion, and the positioning of the strands around closely spaced selvage restraining elements while the strands are fully controlled and without a separate depositing action. An additional objective is to provide a means of high speed strand traversing that minimizes strand abuse. A further objective is to provide a traversing machine that minimizes space requirements beyond the web width.
Though the term "strands" will be used throughout the specifications, this term is meant to include yarns, threads, cords, filaments and other similar materials. Such materials may be either natural or synthetic.